Scalar-tensor models of normal and phantom dark energy

Gannouji, Radouane; Polarski, David; Ranquet, Andre; Starobinsky, Alexei A.

Keywords: reconstruction, Scalar tensor theory

Abstract

We consider the viability of dark energy (DE) models in the framework of the scalar-tensor theory of gravity, including the possibility of having a phantom DE at small redshifts z as admitted by supernova luminosity-distance data. For small z, the generic solution for these models is constructed in the form of a power series in z without any approximation. Necessary constraints for DE to be phantom today and to cross the phantom divide line p = -ρ at small z are presented. Considering the solar system constraints, we find for the post-Newtonian parameters that γPN < 1 and γPN,0 ≈ 1 for the model to be viable, and βPN,0 > 1 (but very close to 1) if the model has a significantly phantom DE today. However, prospects for establishing the phantom behaviour of DE are much better with cosmological data than with solar system experiments. Earlier obtained results for a Λ-dominated universe with the vanishing scalar field potential are extended to a more general DE equation of state confirming that the cosmological evolution of these models rules them out. Models of currently phantom DE which are viable for small z can be easily constructed with a constant potential; however, they generically become singular at some higher z. With a growing potential, viable models exist up to an arbitrary high redshift.

Más información

Título de la Revista: JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
Volumen: 2006
Número: 9
Editorial: IOP PUBLISHING LTD
Fecha de publicación: 2006
Página de inicio: 016
Página final: 016
URL: http://stacks.iop.org/1475-7516/2006/i=09/a=016?key=crossref.c386a6d4e88ef5efa14a8b5dd3c83497
DOI:

10.1088/1475-7516/2006/09/016